Effects of Coal Deformation on Different-Phase CO 2 Permeability in Sub-Bituminous Coal: An Experimental Investigation

Beining Zhang, Weiguo Liang, Pathegama Gamage Ranjith, Wei He, Zhigang Li and Xiaogang Zhang
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Beining Zhang: College of Mining Engineering, Key Laboratory of In-Situ Property-Improving Mining of Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, China
Weiguo Liang: College of Mining Engineering, Key Laboratory of In-Situ Property-Improving Mining of Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, China
Pathegama Gamage Ranjith: Deep Earth Energy Laboratory, Department of Civil Engineering, Monash University, Building 60, Melbourne, VIC 3800, Australia
Wei He: College of Mining Engineering, Key Laboratory of In-Situ Property-Improving Mining of Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, China
Zhigang Li: College of Mining Engineering, Key Laboratory of In-Situ Property-Improving Mining of Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, China
Xiaogang Zhang: Deep Earth Energy Laboratory, Department of Civil Engineering, Monash University, Building 60, Melbourne, VIC 3800, Australia

Energies, 2018, vol. 11, issue 11, 1-25

Abstract: Coal deformation is one of the leading problems for carbon dioxide (CO 2 ) sequestration in coal seams especially with respect to different-phase CO 2 injection. In this paper, a series of core flooding tests were conducted under different confining stresses (8–20 MPa), injection pressures (1–15 MPa), and downstream pressures (0.1–10 MPa) at 50 °C temperature to investigate the effects of coal deformation induced by adsorption and effective stress on sub-critical, super-critical, and mixed-phase CO 2 permeability. Due to the linear relationship between the mean flow rate and the pressure gradient, Darcy Law was applied on different-phase CO 2 flow. Experimental results indicate that: (1) Under the same effective stress, sub-critical CO 2 permeability > mixed-phase CO 2 permeability > super-critical CO 2 permeability. (2) For sub-critical CO 2 flow, the initial volumetric strain is mainly attributed to adsorption-induced swelling. A temporary drop in permeability was observed. (3) For super-critical CO 2 flow, when the injection pressure is over 10 MPa, effective-stress-generated deformation is dominant over the adsorption-induced strain and mainly contributes to the volumetric strain change. Thus, there is a linear increase of the volumetric strain with mean pore pressure and super-critical CO 2 permeability increased with volumetric strain. (4) For mixed-phase CO 2 flow, coupling effects of adsorption-induced swelling and effective stress on the volumetric strain were observed but effective stress made more of a contribution. CO 2 permeability consistently increased with the volumetric strain. This paper reveals the swelling mechanism of different-phase CO 2 injections and its effect on coal permeability.

Keywords: different-phase CO 2; coal permeability; carbon dioxide sequestration; coal deformation (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2018
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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